1. Field of the Invention
The present invention relates to a turbomachine combustion chamber shell ring.
The shell ring in question herein defines a flame tube, which is thus subject to considerable overheating on the inner face thereof, whereas the outer face thereof is crossed by a cool gas flow, originating from the turbomachine compressors and mixing with the combustion gases downstream from the shell ring before entering the turbines.
2. Description of the Related Art
Such a shell ring is traversed by a plurality of types of holes, including dilution holes having a relatively large diameter intended to allow the entry of a portion of the outer flow into the flame tube so as to improve the composition of the combustion mixture, and finer ventilation holes, which are more numerous and distributed on most of the surface area of the shell ring, to also enable the entry of air from the outer flow, but which have the effect of protecting the shell ring from overheating, by forming a flush flow in the downstream direction on the inner face of the shell ring and thus a boundary layer cooler than the combustion gases.
This boundary layer is reformed poorly downstream from the large diameter holes, interrupting the flush flow, and the corresponding portions of the shell ring, all or almost all subject to overheating, are subject to deformation and stress arising from differential expansions, which may give rise to cracks.
The document EP-A-1 703 207 describes a combustion chamber whereon the invention may be implanted. In addition, the above problems are mentioned in the French patent application registered under the number 11 53232 disclosing a modification of the conventional shell ring arrangement to reform the boundary layer immediately downstream from the large-diameter holes and thus relieve the shell ring. A further solution is however proposed with the present invention.